Method of curing bright-leaf tobacco



July 5, 1949. J. B. MOORE, JR 2,475,563

I METHOD OF CURING BRIGHTLEAF,TOBACCO I Filed Jan. 23, 1945 2Sheets-Sheet 1 v V #vvz-NI'OR v JA/VAS 49. moo/95 24 J.. B. MOORE, JRMETHOD OF CURING BRIGHT-LEAF TOBACCO July 5, 1949. 0

Filed Jan. 23, 1945 2 Sheets-Sheet 2 M H H hm hb. llw i A/ TOR/VE YPatented July 5, 1949 METHOD OF CURING BRIGHT-LEAF TOBACCO James B.Moore, Jr., Lexington, Ky.

Application January 23, 1945, Serial No. 574,078

12 Claims. 1

The present invention relates to the curing of tobacco leaves and moreparticularly, to tobacco leaves having the physical and chemicalcharacteristics of tobacco leaves grown in Florida, Georgia, SouthCarolina, the eastern North Carolina belt, the middle belt of NorthCarolina and Virginia, and the old belt of North Carolina and Virginia,said tobacco being known as brightleaf flue-cured tobacco, identified bythe United States Department of Agriculture as types 11 to 14,inclusive, type 11 being divided into sub-types 11A and 11B.

In accordance with the present invention there is provided a method ofcuring tobacco leaves which produces thecured tobacco in a relativelyshort period, said method being characterized by simplicity and economyin operation.

One object of the present invention is to yellow the tobacco in a shortperiod of time while maintaining the relative humidity of the heated airabove about 90% or 95% and below but adjacent the dew point withoutover-ripening the tobacco leaves, that is, spotting said leaves, saidhumidity preferably varying from about 95% to 98%.

Another object is to accomplish the yellowing process in a relativelyshort period of time, preferably varying from 36 to 48 hours, and insome cases in 30, 36 or 60 hours. 7

Another object is to accomplish the yellowing step under the conditionsabove set forth, while utilizing a composite circulating air-treatmentmedium comprising a predominating quantity of recirculated air and asmall quantity of fresh air, just about sufiicient to keep the compositecirculating medium below the dew point, that is, to prevent thecomposite air from being saturated. If the relative humidity approaches100%, water drops out and therefore it is best to operate at 95% to 98%.

Another object is to carry out the yellowing step under the conditionsset forth while circulating the air through the tobacco curing chamberabout every 21/ minutes to about 3 minutes. Another object is to effectthe yellowing step at a temperature inhibiting any substantial drying ofthe tobacco leaves, said temperature being preferably below 100 F. anddesirably 90 F. to

Another object is to dry the yellowed tobacco .in a relatively shortperiod, preferably 24 to 48 2 structure so that the moisture on theinside of the leaves cannot be removed. Preferably, the tobacco duringthe drying period is brought up to a temperature varying between F. andF. although it may be brought up to F. or even F. and in some cases evenup to a temperature of F. But, at the higher temperatures there is adeteriorating change in the tobacco, sealing or facing beginning toappear at about 135 F. or 140 F.

A further object is to effect drying of the yellowed tobacco while usingsubstantially fresh air, that is, no circulating air is used.

Another object is to effect killing out of the tobacco stems in arelatively short period of time, usually varying from about 24 to 48hours, using a composite air medium comprising a predominating quantityof recirculated air and a small quantity of fresh air to prevent thecomposite air medium from building up a high humidity.

A further object is to recirculate air during the drying period everyminute to 2 minutes, and preferably 1 minute, that is, the air thatenters the chamber at the beginning of the minute period is completelyremoved from the chamber at the end of 2 minutes and a new cycle starts.

Another object is to effect killing out below For F., and preferably,below 150 F. under the conditions set forth.

In order that the present invention may be more clearly understood,reference is made to the accompanying drawing wherein Fig. 1 is atransverse section more or less diagrammatic of an apparatus forcarrying out the present invention, Fig, 2 is a section taken on theline 22 of Figure 1 and Fig. 3 is a cross section takenon line 3-3 ofFig. 1.

Referring to the drawing, in represents a tobacco barn in which tobaccoleaves II are hung, the latterbeing tied on sticks, the sticks oftobacco being supported on tier rails l2. The barn l0 is provided withan exit duct I3 and a return air duct M, the former being provided witha pressure damper [5. The return air duct M is also equipped with aregulating damper l6 and the return air duct has an opening H with aslide cover l8 by which means fresh air can be admitted to the duct andto the system. A pressure blower I9 is operatively connected to the ductl4, said blower being equipped with an electrical or gasoline motor 2|].The blower is operatively connected to the base of the jacket 22 of thefurnace 23, the latter being equipped with a vaporizing oil burner means24 which is connected 3 to the heat exchanger '25 provided with a fluepipe 26 passing through the roof of the shed 21. Operatively connectedto the bonnet of the furnace is a supply duct 28 provided with a limitcontrol 29, said control functioning to cut off and on the oil burner ata predetermined temperature, usually within a range of 100 to 200 F. Theduct 28 passes into the barn l0, preferably centrally thereof, at thepoint 281) and is connected by means of a duct 28a to an auxiliarysupplying duct 30 provided with a splitter damper 3|. The aux; iliarysupply duct is operatively connected to dis tributing ducts 32 and 33respectively, said ducts,

being of any appropriate shape but preferably:- triangular, and thesides thereof are provided with staggered apertures 34 whereby air isintroduced into the barn and distributedevenly over. g

the tobacco leaves therein. Suitably disposed outside of the tight barnI0 is the remote bulb-ther mostatic temperature control 35, preferablyhaving a range from about 80 to 180.?;F.1

The .oil burner is .provided. with an automatic fiow metering valve 36which is connected by meansof a pipe 31to the oil tank38. The thermostat35 controls theoif and on magnetic valve of the flow control valve. 36.

The following is a specific example illustrating the present invention:

The barn II] which .is gas tight is filled with about 6,000 pounds oftobacco, the amount which can be introduced into a barn which is 16, x16x 16.. The tobacco leaves are leaves which have been primed from thetobacco stalks and tied onto sticks, said sticks. being hun ,over. tierrails until thebarn is filled. ,The field ripened tobacco Q.

is introducedinto the .barn ID. as quickly as pos, sible after thepriming. The object of introducing the tobacco leaves into the.barn IDas soon as. possible after the priming is toprevent deterioration. ofthe tobacco. Itmay. be stated that tobacco of thecharacter being,treated. by the present invention is rather. perishable, it beingWell-known that if the tobacco is leftin the fields and subjected .tosunlight for a period of a days time, .itwill. materially depreciate-invalue. It is therefore desirable, in order .to preserve the high qualityof the tobacco, that the tobacco be introduced into. the barn as .soonaspracticable.

Itgislquite desirablethat the process of yellowing, drying and killingthe tobacco be started as soon as practicable. after the ,tobacco leaveshave beenintroduced into the barn J0; However.

if thetobacco in the barn is kept dark and away.

from-sunlight no appreciable harm ,will result in 24; to 36 hours.However, as.v stated, itis the preferred procedure. that after. thebarnis filled with about 6,000 pounds of field ripened tobacco leaves,to initiate the treatment of the tobacco leaves in accordance with thepresent invention. It may. be stated that the field. ripened tobaccocontains between 80% to 88% of moisture. and

one of the objects of .thepresent invention is to. complete the ripeningof the tobacco and then'to;

duct 14. Damper I6: isz-placedin its fullopenposition to allow freeaccess .of return air from, the barn ID to the return air-.duct Ill..The belt connecting blower l9 and the motor 20 is then adapted. onoperation to deliver about 1,500 C. F. M. of air composed of 100 cubicfeet of fresh air and 1,400 cubic feet of return air to the furnace 23.The small amount of outside fresh air functions to keep the relativehumidity of the circulated air from reaching the dew point where, as iswell-known, condensation occurs. If condensation forms on the tobaccoleaves, the latter become oxidized and assume what is known in the artas a spongy state. As stated, the function of the fresh air is to keepthe recirculated air from-reaching the dew point and therefore,

functionally stated, enough outside fresh air' is started, the blower l9having been placed in.

operation. The mixture of airproduced as above set forth thenbegins tocirculate through the barn l0.

It is desiredto point out that the relative humidity of therecirculatedair is maintained within a range which will allow the tobacco-leaves toyellow\ without any substantial. drying-.. In

accordance with the present invention it is found.

thatthe most satisfactory results are obtained during the yellowingperiod when the recirculated air is maintained ,with-a relativehumidity. of 95' to 98%. Less. satisfactory results: are. obtained whenthe humidity is maintained between to Itis therefore desired not tolimit the invention to.-,a rangeiof. humidity during yellowing of 95 -to9,8%.

When-processing a batch of 6,000 pounds of tobacco it has been foundthatoperating with the above uantity of air and under. the above conditionsof humidity, the tobacco is yellowed in a period ranging from about 36to 60 hours.

Naturally, this period will vary.- somewhat tiependingon thephysical andchemical characteristics of the tobacco,.the size .of the tobaccoleaves, and theirstate of field ripeness. If the tobacco leaves arethick and the stems are large and,

only partially ripened, the time of yellowing under the, conditions'setforth will approximate the period of 60 hours; thinnerand the stemsarev smallen-the time of yellowing under the conditions above set forthmay decrease to about 50;.hours; Tobacco leaves have been satisfactorilyyellowed using thepresent inventionywhemtreated under the conditions.set forth for a periodof. 36.and .40hours respectively. Depending onthe above circum-- stances the time of.- yellowingunderthe-conditions,-.set -for.th nayvary froml36- toes hours, 36:

l to 55 hoursor 36 to 60 hours;

It is desiredto-point outthat, for. a burner of thesize setforthyandoperating under'the con-- ditions set forth that there is asubstantially completgrecirculation .of air in; the barn every 2% to .3minutes.- This rateotair movement. through crea ed. sothattheai isrecirculated atthe rate;

If .the tobacco leaves are above set forth, that is, a completerecirculation of all the air in the. barn occurs every 2 to 3 minutes.Using a barn x 20' x 16', and having a. Volume of 6,400 cubic feet, theamount of cubic feet of air circulated through the barn would beincreased to 2,100. During a threeminute cycle air would be recirculatedat the rate of 6,025 cubic feet of recirculated air and 375 cubic feetfresh air, making a total of 6,400 cubic feet for the three-minutecycle. Using the 16' x 16 x 16 barn for a three-minutes period the totalamount of air circulated would be 4,500 cubic feet of which 300 cubicfeet would be fresh air and 4,200 cubic feet recirculated air.

When the tobacco leaves reach their desired yellow color as indicated.by visual inspection, the yellowin step is terminated and the dryingstep is initiated by first setting the thermostat to about F. to F. orF. Thereafter the damper I 5 in the exhaust duct is is placed in itsfull open position, the return air damper I6 is placed in its fullclosed position, and the belt connecting the motor and fan is placed inits maximum position for the full operation of the blower. Air is drawnin through the opening I! into the return air duct l4 and is forced bythe blower l9 through the duct 28, preferably at the rate of 4,000 C. F.M. From the duct 28 the air traveling at the rate set forth isintroduced into the barn 10, preferably for a period varying between 24to 48 hours. The air functions to dry the tobacco leaves and thetemperature of the tobacco will gradually increase during the timeperiod set forth from 95 F. to about 120 F. or 130 F. It is desired topoint out that by maintaining this lower temperature and increasing theair flow across the tobacco the rate of drying is increased withoutdamaging the cell structure of the tobacco and, the volatile oils of thetobacco are retained. Therefore, while 120 F. or 130 F. has been setforth as the maximum or preferred temperature durin the drying period,it is recognized that even using the exeedingly high rate of 4,000 cubicfeet of fresh air per minute that the temperature of drying may beincreased to 130 F., F., or even F. Experiments have been carried outusing a drying temperature as high as F. or F. but the best and mostsatisfactory results .are obtained when using a drying temperature of120 F. to 130 F. If the temperature is increased over about 120 F. or130 F., with each increase there is usually a deteriorating change inthe quality of the tobacco until complete facing occurs which seals thecell structure so that moisture on the inside of the leaf cannot beremoved. This is highly undesirable.

During the drying period the humidity of the air leaving the exit ductl3 will change from approximately 98% relative humidity at theinitiation of the drying period to approximately 25% to 30% andsubstantially all of the moisture has been taken out of the tobaccoleaves, but a considerable amount of moisture still is left in thetobacco stems. The amount of moisture present in the leaves will dependupon the particular kind of tobacco being treated and its growinghistory. During the drying period the air in the barn is changedapproximately every minute, this having given the most satisfactoryresults. The general statement as to the frequency of change is that theair may be changed in the barn l 0 during a period ranging in lengthfrom 45 seconds to about 1, 1 or 2 minutes. The rate of drying may beincreased to approximately one-half minute air change but care wouldhave to be exercised to inhibit facing of the tobacco. It should beborne in mind that the rate of evaporation of the moisture fromthetobacco leaves should be governed by the total amount of heat beingintroduced into them and if this rate is accelerated beyond a certainpoint the cell structure would be damaged and facing would occur.

After the tobacco leaves have been properly dried it is necessary to drythe tobacco stems and this stage is technically known as the killing outstage. At the end of the leaf-drying period, the damper l 5 and exitduct l3 are practically closed, that is, only a small opening remainssuflicient to bleed off the excess air from the barn. The damper It inthe return air duct I4 is then placed in its full open position and theslide damper I8 is practically closed to within one or two inches of itsfull shut position. This will allow a small quantity of fresh air toenter the return air duct l4 and be mixed with the recirculated air fromthe barn l0. At approximately the same time the thermostat 35 is set toabout 150 F. to 190 F. The limit control 29 is then set in its full openposition and preferably at 250 F. During the killing out period theobject is to gradually increase the temperature of the tobacco and ofthe air circulating in the barn to that point which is suflicient toremove the remaining moisture in the tobacco stems, preferably thetobacco temperature and that of the circulating air being allowed toreach about 150 F., but may be as high as F. of F. After the moisturehas been removed from the tobacco leaves during the drying period, theincrease in temperature will not have any deleterious effect upon theproperties or the quality of the dried tobacco leaves. During thekilling out period, the air is circulated at approximately the same rateas used during the drying period, it being pointed out, however, thatduring the drying period all fresh air is used and that during thekilling out period only about 10% fresh air is introduced into the barn.In other words, at any given period of time the circulating air in thebarn comprises 90% of old recirculated air and 0% of fresh air. Duringthe killing out period a small portion of the total contents circulatedthrough the barn I0 is exhausted through the exhaust duct l3 and to compensate for this loss of air, a small amount of fresh air is let intothe barn to keep the circulated air from building up to a high humidity.Usually it is best to maintain the relative humidity of the aircirculating in the barn l0 during the killing out period as low aspossible and generally within a range of 10% to 15%. At the initiationof the killing out period the humidity of the circulating air willprobably be in the neighborhood of 20%, 25% or 30%.

The killing out period will usually range from 24 to 48 hours dependingupon the physical and chemical characteristics of the tobacco anddepending on the thickness of the stems. It is preferred that during thekilling out" period that there be a complete air recirculation everyminute although here again this may be reduced to onehalf minute or maybe increased to 1%, 1 1%, or 2 minutes. The total amount of aircirculated per minute through a barn 16' x 16 x 16' is 4,000 cubic feet,of which approximately 7 to 15%, but preferably 10% is fresh air.

It is desired to point out that the tobacco stems should besubstantially completely dried so that when the tobacco is exposed tothe unconditioned air it will not readily absorb moisture and in ture ofthe tobacco below a maximum of about 170 F. by passing over the tobaccoa current of heated air, the relative humidity of which decreases duringthe killing out to a relatively dry state.

2. The method of curing tobacco consistingof stems and leaves, saidtobacco having the characteristics of tobacco grown in Florida, Georgia,South Carolina, the eastern North Carolina belt, the middle belt ofNorth Carolina and Virginia, and the old belt of North Carolina andVirginia, said tobacco being known as bright-leaf fluecured tobacco,comprising confining the tobacco in a Substantially airtight curingchamber having inlet and outlet ducts, yellowing the tobacco bysubjecting it for a period varying from about 36 hours to about 60 hoursto a current of heated air which inhibits any substantial drying of thetobacco and has a relative humidity above about 95% and below butadjacent the dew point, said current of air comprising a predominatingquantity of recirculated air and a small quantity of fresh air whichkeeps the composite circulating air-medium below the dew point, dryingthe yellowed tobaccofor a period of time varying from about 24 to about48 hours while gradually increasing the temperature of the tobacco toabout 130 F. while simultaneously subjecting the tobacco to a current ofcirculating fresh air, the relative humidity of which at the outlet ofthe curing chamber is gradually reduced from adjacent the dew point to arelatively dry state, and subjecting the so-treated tobacco to acirculating current of heated air for a killing out period of timevarying between from about 24 to about 48 hours while graduallyincreasing the temperature of the tobacco below a maximum of about 150F. by passing over the tobacco a current of heated air, the relativehumidity of which decreases during the killing out to a relatively drystate.

3. The method of curing tobacco consisting of stems and leaves, saidtobacco having the characteristics of tobacco grown in Florida, Georgia,South Carolina, the eastern North Carolina belt, the middle belt ofNorth Carolina and Virginia, and the old belt of North Carolina andVirginia, said tobacco being known as bright-leaf fluecured tobacco,comprising confining the tobacco in a substantially airtight curingchamber having inlet and outlet ducts, yellowing the tobacco bysubjecting it for a period. varying from about 36 hours to about 60hours to a current of heated airwhich inhibits any substantial drying ofthe tobacco and has a relative humidity varying between from about 95%to about 98%, said current of air comprising a predominating quantity ofrecirculated air and a small quantity of fresh air which keeps thecomposite circulating airmedium below the dew point, drying the yellowedtobacco for a period. of time varying from about 24 to about 48 hourswhile gradually increasingthe temperature of the tobacco to about 130 F,while simultaneously subjecting the tobacco to a current of circulatingfresh air, the relative humidity of which at the outlet of the curingchamber is gradually reduced from adjacent the dew point to a relativelydry state, and subjecting the so-treated tobacco to a circulatingcurrent of heated air for a killing out period. of time varying betweenfrom about 24 to about 48 hours while gradually increasing thetemperature of the tobacco below a maximum of about 170 F. by passingover the tobacco a current of heated air, the relative humidity of whichdecreases during the killing out to a relatively dry state.

4. The method of curing tobacco consisting of stems and leaves, saidtobacco having the char acteristics of tobacco grown in Florida,Georgia, South Carolina, the eastern North Carolina belt, the middlebelt of North Carolina and Virginia, and the old belt of North Carolinaand Virginia, said tobacco being known as bright-leaf fluecured tobacco,comprising confining the tobacco in a substantially airtight curingchamber having inlet and outlet ducts, yellowing the tobacco bysubjecting it for a period varying from about 36 hours to about 60 hoursto a current of air having a temperature varying from about F. to aboutF. and a relative humidity above 90% and belowbut adjacent the dewpoint, said current of air comprising a predominating quantity oirecirculated air and a small quantity of fresh air which keeps thecomposite circulating air-medium below the dew point, drying theyellowed tobacco for a period of time varying from about 24 to about 48hours while gradually increasing the temperature of the tobacco to about130 F. while simultaneously subjecting the tobacco to a current ofcirculating fresh air, the relative humidity of which at the outlet ofthe curing chamberis gradually reduced from adjacent the dew point to arelatively dry state, and subjecting the so-treated tobacco to acirculating current of heated air for a killing on period of timevarying between from about 24 to about 48 hours while graduallyincreasing the temperature of the tobacco below a maximum of about 170F. by passing over the tobacco a current of heated air, the relativehumidity of which decreases during the killing out to a relatively drystate.

5. The methodof claim 1 wherein the circulating air is completelycirculated through the curing chamber during the yellowing period every2% minutes to 3 minutes; during the drying period every of a minute to 2minutes; and during the killing out period every 1 minute to 2 minutes.

The method of claim 1 wherein the circulating air is completelycirculated through the curing chamber during the yellowing period every2 minutes to 3 minutes; during the drying period every 1 minute; andduring the killing ou period every 1 minute.

'7. The method of curing tobacco consisting of stems and leaves, saidtobacco having the characteristics of tobacco grown in Florida, Georgia,South Carolina, the eastern North Carolina belt, the middle belt ofNorth Carolina and Virginia, and the old belt of North Carolina andVirginia,

said tobacco being known as bright-leaf fluecured tobacco, comprisingconfining the tobacco in a substantially airtight curing chamber havinginlet and outlet ducts, yellowing the tobacco by subjecting it foraperiod varying from about 36 hours to about 60 hours to a current ofheated air which inhibits any substantial drying of the tobacco and hasa relative humidity above about 90% and below but adjacent the dewpoint, said current of air comprising a predominating quantity ofrecirculated air and a small quantity of fresh air which keeps thecomposite circulating air-medium below the dew point, drying theyellowed tobacco for a period of time varying from about 24 to' about 48hours while gradually increasing the temperature of the tobacco tobetween about -and F. while simultaneously subjecting the tobacco to acurrent of cir- QA-ZMQQ acteristi s o a co rown F ori a G o ia.

South Carolina, the eastern'North Carolina belt the middle belt ofNorthgarolina and Virginia and the old belt ofaNorth Gar-olina, andVirginia, said tobacco being; known as bright-leaf fluecured tobacco,comprising confining the tobacco a I in a substantially, airtight curingchamber havn inlet and outletduc s, yell win -the oba co y subiectin itfor. ap ri d va ying from abou 36 hours to. about fiflihours to a.current. or heat d.

air which inhibits, anysubstanti-al dryin of the tobacco and has. arelative humidity above about 90% andbelow but adjacent thedewpoint,said current of air comprising a predominating quantity of recirculatedair and-a small quantity'ofifresh air which keeps.rthecompositecirculatingair-j medium below the; dew point-,drying-theyellowed tobacco for a period 015 time varying. from about 24 to about48 hourswhi-le. gradually increasing the temperature. of-the tobacco,tobetween about 120? and 130..F..while simultaneously subjecting" thetobacco to a currentof: circulating fresh air, the relative humidity ofwhich at the, outlet; of' the curing chamber is graduallyreduced fromad. jacent the. dew point tola relatively dry state, and subjecting the.so-treated ,tobaccoito; a circulatin current at heated. air .for. a.flrillinghout -period. of time varying between from. about? 24 to about48 hours while graduallyincreasingthei temperature, of the tobaccobelowama'ximum. of. about 170-911 by passing over the tobacco a currentotheated air, the relative humidity. of which. decreases during. thekilling. out to aerelativelye. dry state.

9'. The method oficuringztobaccol consistingofi stems and leaves, said.tobaccohavingthel characteristics of. tobacco grownin Florida,-Georgia, South Carolina, the eastern North-Carolina, belt, theemiddlebelt. t North 'Garolina. and Virginia, and. the old belt ofiNorthCarolina and Virginia, said: tobacco. being known as:bright-leaffluecured. tobacco,.coniprising. confining the tobacco.

in a substantially. airtight curing; chamber. having. inlet andoutlet.ducts yellowing the tobacco by subjectingit for. aperiod varying.trom about 36 hours to aboutffiodhour's to a. current. or. heated airwhich inhibits. any substantialidrying: of the tobacco. and lhasarelative. humidity above. about 90% and below but. adjacentthe'.;dW;pDint-, .S&ld' current of airicomprising a predominatingquan:tity of recirculated. air iandifa small. quantity of: fresh air keepsthe composite. circulating airemedium below tlieadewipoint; dryin'githeyel-l lowed tobacco/tore a period? of: time varying from. aboutles toabout id-hours; while. gradually in: creasing the. temperature ofi-thetobacco; tobee tweenv about Iftand. 140% E. whilesim ultaneouslysubjecting,the-tobacco to a currentloflcirculatingi-fi esh air, therelative humidity of which at the. outlet? of the curing, chamber isgradually reduced from. adjacent thedewpointtoa rela.. tively dry state,andcsubjectinggthe. so'etreated tity ofrecirculated airanda ater-zeta acirculat n curr n f heated ai 117 a b ll n u relie Qf' ime var in b teen om about 4 tqabuu abo rs whi gr dual y 'e r e i-a th emeera e o heheat b owa maximum of about 170 F. by passing overrt he o a o. curren oa ed 1 3, he re a iv humidity of which decreases during-the ,killing outto a relatively dry state.

10. The method of curing tobacco consisting of-stems and leaves saidtobaccohavingthee "f acteristics of tobacco grown in Florida; Georgia,South Carolina, the. eastern-North Carolina; belt the middle belt ofNorth Carolina and Virgin and the old belt of. North Carolinaandvirginia said tobacco being. known as brightrleaf fluee curedtobacco, comprisingconfining the tobacco; in. a substantially airtightcuring-chamber have inginlet and outlet ducts, yellowing the tobacco; bysubjecting it for a period varying from. about; 3 ur to a t 6.0 h s a crren heated: air which inhibits any substantial drying ogthe;

0% nd l w- -t; e ia entth 11 at current of aireompri sing. a predominatquali:

that fresh air which keeps; the comp osit i airFmediu-m below; the dewpoint;- lowed tobacco, for a period; ofti I M I about 24= to about 4-8hours wlg ilegra creasing the temperature ct thetebac tween about and1403 1. while s is y ubi t n eto a e to a curr n v cul-ating .tresh air,the relative humidity at e u t o eu ee Qbam eree allr reduced fromadjacent the dew nt-toar tivelydrystate, and :killing outiGthe-tob stemso f the so-treated tobacco by subjectingqthe; at r to. a c cula i r e e-hea ed air h t: radua cr as n he t mhe e en b o a m x mum o 7- ing ofsaidl eated current of air ere a yehu i o t e hea. ts du th in o tpee il -errs a h a siheated air e -reela e i nd; b t en /2=%. a d cash ..1:-T metho of wi n tobac onsi ting: efi t ms anc a es a d qhaceoh e r ti so ac erow E1. afieore a; Sou h e r l a; he s rn No h; Ca ina belt, the.middle beltot North Carolinaan dtirginia; and the oldbelt of NorthCarolina and; Virginia said tobacco being k -nown as bright' leaf;flue-N cured tobaeco, comprising confining the. tobacco in asubstantially airtight curing chamber have ing inlet and: outlet ducts,yellowing the tobacco by. subjecting it for a period varyi,-f;rornabout. 36 hours to about 60 hours-to a-cur nt of ,l eated; a rwhich inhibits substantial-dryingOfgtht tobacco and has. a relativehumidity alcoye about 0 andbemw t d acen ;theoewrqin curr nt ia r comprin a redem netina ty etres rqelated a rand a sma h ua ti r i re a wis kees the compo ite q sr ahe e eme ium l w th de wi te time ravel lowedtobacco for a p riod of time varying iijbm about 24 to about 48 hourswhile gradually in creasing the temperature of the tobaccoto 'b' e-.tween about 120 and F. while simultaneously subjecting the tobacco to acur-rntof circulating fresh air, therelativehumidity-ofi.which at theoutlet of the curing chamber is gradually reduced from adjacent the-dew,point, to a. rela-' tively dry state, and killing; out" the tobaccostems. ot the. sol-treated: tobacco! by subj ectingi thelatter to acirculating current of heated air comprising recirculated air andbetween 7 and 15% of fresh air for a "killing out period of time varyingbetween about 24 and 48 hours while gradually increasing the temperatureof the tobacco below a maximum of 170 F. by the passing of said heatedcurrent of air over the tobacco, the relative humidity of the heated airdecreasing during the killing out period to a relatively dry state.

12. The method of claim 11 wherein the circulating air is completelycirculated through the curing chamber during the yellowing period every2 minutes to 3 minutes; during the drying period every of a minute to 2minutes; and during the killing out period every minute to 2 minutes.

JAMES B. MOORE, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

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